POSITIVE RAYS
He obtained, too, direct evidence of these charges, and by measuring the deflection tinder electric and magnetic forces, he obtained io4 as the maximum value of ejm; this is the value for the hydrogen atom in electrolysis. I thought the study of these rays might throw light on the nature of the carriers of positive electricity. Are they, for example, all of one type, like the carriers of negative charges ? The method I used for this purpose was to send a narrow pencil of rays through the space between two parallel brass plates and apply in the space between these plates electric and magnetic forces, both at right angles to the plates. If the plane of the paper is at right angles to the beam of electrified particles, and also to the plates, and if AB and CD are the lines of intersection of this plane and the plates, then, as the beam passes between the plates, the electrified particles will be acted upon by two forces at right angles to each other : a horizontal one due to the electric field and a vertical one due to the magnetic. The rays when they
strike against a photographic plate produce a spot where they hit the plate* Suppose this plate is placed at right angles to the beam of rays, and that when neither electric nor magnetic forces are acting, the rays hit the photographic plate at O, and that when the electric and magnetic forces are on, O is displaced to P.